Air-exhausting mechanism for labeling machines



E. L. SMITH AIR EXHAUSTING MECHANISM FOR LABELING MACHINES June 8 1926.

Filed Nov. 15 1921 3 Sheets-Sheet 1 INVENTOR BY 7W ATTORNEYS June 8 1926. 1,587,868

E. L. SMITH AIR EXHAUSTING MECHANISM FOR LABELING MACHINES Filed Nov. 15, 1921 3 Sheets-Sheet 2 BY WWW.

ATTORNEYS June 8 1926.

E. L. SMITH AIR EXHAUSTING MECHANISM FOR LABELING MACHINES Filed Nov. 15, 1921 3 Sheets-Sheet 5 INVENTOR ATTORNEYS Patented June 8, 1926.

UNITED STATES PATENT OFFICE.

ELMER LOVELL SMITH. OF SPRINGFIELD. MASSACHUSETTS. ASSIGNOR TO PACKAGE MACHINERY COMPANY, OF SPRINGFIELD, MASSACHUSETTS, A. CORPORATION OF MASSACHUSETTS.

AIR-EXHAUSTING MECHANISM FOR LABELING MACHINES.

Application filed November 15, 1921. Serial No. 515,265.

The present invention relates, in general, to machines for applying labels or wrappers to articles of various kinds and is espe' cially concerned with labeling machines of 5 the type in which the labels are stacked face-tofacc in a supply magazine and means in the nature of a suction picker device is periodically operated to move a portion of the foremost label of the stack into posi- 19 tion to be seized by the label applying mech anism. More particularly the invention relates to air exhausting mechanism for use in connection with the suction label positioning device or devices of machines of the type above mentioned.

The object of the invention is to provide certain new and useful improvements in the construction and mode of operation of air exhausting m chanism for the purpose of rendering the same particularly applicable for use in connection with certain types of labeling or wrapping machines.

The invention consists in the features of construction and combinations and arrangements of parts hereinafter described and claimed, the advantages of which will be obvious to those skilled in the art.

The several features of the invention will be best understood from a description of the preferred embodiment thereof, illustrated in the accompanying drawings, in which the invention has been shown as applied to a labeling mechanism of a well known type, an example of which is disclosed in a co pending application, Serial No. 503,262,

filed September 26. 1921, by the present applicant and F. B. Fuller, jointly.

In the drawings Fig. 1 is a view, partially in side eleva tion'and'partially in section, of an air exhausting mechanism embodying the present invention in its preferred form and illustrating its usein connection with the labeling mechanism of said prior application;

Fig. 2 is a plan view, on a reduced scale, of the mechanism shown in Fig. 1.

Fig. 3 is a plan view of one of the label applying drums and associated mechanism showing certain details of construction omitted in Fig. 2;

Fig. 6 is a perspective view, partly broken away, of one 'of the suction tubes of the lab-cl applying mechanism; and 4 Fig. 7 is a View, partly in side elevation, of the label applying drums and assodatml mechanism shown in Fig. 3.

The labelling mechanism illustrated in the drawings, in common with that of the prior application above referred to, is arranged to cooperate with the mechanism of a wrapping machine to complete the wrapping of a rectangular article by securing labels or seals to its opposite ends after the ends have been partially covered by the wrapper. Except for the details of construction and op eration of the air exhausting mechanism, the parts shown in the drawings are like those disclosed in the prior application above referred to but in order to enable the present invention to be completely understood, the construction and operation of the labeling mechanism will be described in more or less detail herein.

The label-applying mechanisms are indicated generally at 2 and are arranged in duplicate, one at each side of the machine. Both label-applying mechanisms are identical in construction and mode of operation and accordingly only one of them will be hereinafter described specifically.

Each label-applying mechanism 2 comprlses a magazine 6 for holding. a supply of'labels, and a label-aflixing device 4, in the general form of a drum, which is rotat able about a vertical axis between the magazine and the feel table Fof'the wrapping machine (Fig, 7). The device or drum 4 is provided with nippers for seizing a label in the magazine and causing it to be with drawn therefrom, and the drum is rotated in such a manner that the label will be drawn over a portion of the cylindrical $114311 0f the drum and later rolled'against the end of an article by the rotation of the drum as the article is advanced into ongagement therewith. The label-ailixing drum is provided with three label-seizing nippers and is intermittently rotated through steps of one hundred and twenty degrees and the nippers are successively caused to seize the end of a label at each stopping position of the drum. A label is removed from the magazine 6 in one partial rotation of the drum and aflixed to an article at the next partial rotation of the drum.

The labels are supported on edge in the magazine 6 between a front plate 3 (Fig. 4) and a follower 5, the latter being constantly urged in a forward direction by any suitable means to advance the stack in the magazine as the labels are successively removed from the forward end thereof. The front plate 3 is cut away at one edge to provide a space 7 through which the foremost label may be removed from the magazine, (see Fig. 5). The labels are acted upon, one at a time, by means of a vertically disposed picker device in the formof a suction tube or plate 8 which is mounted adjacent the opening 7 and which is operative to move the forward edge of the margin of the foremost label into the field of operations of the nippers of the label-aflixing drum 4. The drum 4 coinprises three segmental plates 9 which are concentrically mounted on. a vertical rotary shaft 13. Each plate 9 terminates at one ot'its vertical edges in a fixed jaw 15 that is adapted to cooperate with a movable nipper 17 so that the edges of the labels may be seized thereby.

The suction tube 8 is illustrated in detail in Figs. 5 and G and may be of any well known construction, having a flattened perforated face against which the labels are to be drawn. The suction tube is adapted to be rocked about its vertical axis and is normally disposed in the angular position illustrated by dotted lines in Fig. 5. Vhen in this position, the air is exhausted therefrom and the marginal portion of the foremost label in the magazine 6 will be drawn against the perforated face of the suction tube. The suction tube is then rotated into the angular position shown by full lines in Fig. 5, swinging said marginal portion of the label outwardly into position to be grasped by one of the gripper fingers or nippers 17 carried by the label-affixing devices 4. Inasmuch as each device 4 carries three nippers, the cam by which the suction tube is oscillated is designed to swing the suction tube forwardly three times at each revolution of the drum. This cam is fixed to the drum 4 as shown at 18 in Fig. 3 and is cooperatively engaged by a cam roll 19 carried by an arm 21 projecting from the suctiou tube.

labcl-aflixing drum,

Each nipper 17 is carried by a vertical rockshaft 23 and is constantly urged into cooperative relation with its respective fixed jaw 25 by a spring 27 acting upon an arm 29 lixcd to the rockshaft :23. At its lower extremity each rock-shaft 23 has aflixcd thereto a. lateral projection 3l (Fig, 4) adapted to ride against the periphery of a stationary cam 32 With this construction, the nippers 17 will be opened by the action of the cam 3-53 before they are moved by the rotation of the. drum into the position to some a label and thereafter, as the projections 31 pass beyond the influence of the cam 33, the nippers are suddenly closed by their springs 27 to seize the label presented thereto by the suction tube 8. This last mentioned operation occurs just prior to the completion of each rotary step movement of the label-afiixing drum which almost immediately thereafter comes to a complete stop. The nippers are thus enabled to securely grip the labels and inasmuch as the start of each step movement of the drum is comparatively slow as will hereinafter be explained, there is no tendency for the nippers to pull away from the labels. The nippers or fingers 17 are preferably constructed of light spring steel and provision is made to insure the spring nippers against possibility of breakage due to continued bending thereof as they are suddenly brought into contact with the fixed jaws 25 by the force of the springs 27. To this end, a rigid finger (Fig. 5) is secured to each rock shaft 23 and this finger carries a stop screw 51 which is adapted to cooperate with a sto shoulder 53 on the drum to take the shocli of the closing movement of the nipper. The screw 51 is adapted for adjustment so that when the nipper has closed, it will yield sufiiciently to firmly grip the label but not enough to bend itself to any appreciable extent and consequently there is no tendency for it to be come weakened from continued use.

' A coating of glue is applied to the outer faces of the labels as they are being rotated by means of the label-afiixing drums from the magazine 6 into engagement with the ends of the articles on the feed table. To this end, a glue pot 55 (Fi 3) is suitably supported adjacent the labe -aflixing device and a vertically disposed glue roll 57 is located in an opening in one of the side walls of the glue pot, the arrangement being such that when a label is fed by one of the segmental plates 9 toward the article on the feed table, the label will ride over the surface of said glue roll.

To insure the pro er application of glue to the face of the lube the glue roll 57 is positively driven' during the rotation of the y means of intermeshing gearing comprising a pinion 59 (Fig. 4) secured to the lower trunnion of the glue roll, and a gear 61, secured to the intermittently rotatable shaft 13.

The drums of the two labelapplying mechanisms 2 are rotated through successive rotations of one hundred and twenty degrees each, by means of the following mechanism. A bevel gear 63 (Fig. 7) is secured to the lower end of the drum shaft 13 of each of the label-applying mechanisms. Meshing with each bevelgear 63 is a bevel gear 65 that is secured to a transverse shaft 67, said shaft being journaled in hearings in the side frame members of the wrapping machine and the gears 65 being located on the shaft adjacent the inner sides of said frame members. At one end of the shaft 67, near the outer side of the adjacent frame member is secured a ratchetwheel 69 having three notches equally spaced apart in its periphery. The ratchet wheel 69 is actuated by a pawl 71 which is pivotally mounted upon a pawl carrier 73 that is mounted to oscillate freely upon the shaft 67. The hub of the oscillatory pawl-carrier arm 73 has formed thereon a rack segment 75 and meshing with this rack segment is a rack 77 carried by a link 79.

' v The link 79 is pivotally mounted at one end,

upon a crank-pin 81 carried by a disk 83 which is fast upon one end of a shaft 85 that is connected with the main drive shaft of the wrapping machine. The other end of the link 79 is provided with a longitudinal slot 87 through which the shaft (37 extends. The slotted end of the link 79 is confined between the ratchet-wheel 69 and a collar 89 that is secured to the end of the shaft 67. With the above-described construction, one third of a revolution will be imparted to the shaft 67 at each rotation of the continuously operating shaft 85. It will be apparent that one half of the rotation of the shaft 85 will be effective to advance the pawl 71 in a direction to effect partial rotation of the ratchet-wheel 69 and shaft 67, while during the succeeding half turn of the shaft 85 the pawl .71 will be retracted idly over the ratchet wheel and the label-affixing drums will remain at rest. It will also be seen that the arrangement of the crank-pin 81 and the connections to the shaft (37 are such that the label-affixing drums will start gradually from their positions of rest and reach a maximum rate of rotation at the middle of their feed movements. By reason of the slow start of rotation of the drums there is no tendency for the nippers carried thereby to be pulled out of holding engagement with the labels. A belt 90 disposed in a vertical plane at either side of the bed F of the machine is supported by the drums 91 rotatable on vertical axes while other driving drums,

not shown, are in engagement with the belts and serve to drive the belts which receive therebetween the articles after the end labels have been applied thereto.

To enable the picker dcvices or suction plates 8 to perform their functions they are severally connected with an air exhausting mechanism 10 which is supported above the wrapping machine and is operated in timed relation with the wrapping and labeling mechanism. To this end, the air exhausting mechanism is operatively connected in a manner hereinafter described with an oscillatory arm 12, the latter being pivoted at ll to a member 16 of the frame of the wrapping machine and constituting a portion of the feed mechanisn'i for advancing the articles while they are being wrapped and labeled.

The various features of the present inven- 55 tion are embodied in the air exhausting mechanism 10 which comprises a pump of the reciprocating piston type that will now be described. As shown in Fig. 1, a pump cylinder 20 is fitted with a piston 22 carried at one end of a piston rod 2% which extends through an elongated bearing 26 in the cylinder head 28 and is pivotally connected at its opposite end to the oscillatory arm 12. The oscillatory arm 12 swings toward the right from the position shown in Fig. l, and to enable the pivoted end of the piston rod 2st to swing with the arm, the cylinder 20 is mounted to rock slightly as the arm 12 oscillates. To this end, an car 30 depending from the cylinder 20 is pivoted upon a stud 32 carried by an arm 34, the latter extending rearwardly from a cross rod 36 to which it is rigidly secured. The cross rod 36 extends above the path of the articles acted upon by the wrapping and labeling mechanisn'i and is supported at its ends by means of brackets 37 rising from the frame 38 of the wrapping machine. As shown, the frame member 16 of the wrap no ping machine is supported at its rear extremity by the cross rod- 36.

The suction plates 8, which are fiat and are perforated in the usual manner, are carried by cylindrical tubes 39 which are mounted to rock in vertical bearings foru'ledin brackets 44) which support the magazines 6 and rise from tables 41 that are secured to the frame of the wrapping machine and support the labeling mechanism. The suction tubes 39 are rocked to bring the faces of the suction plates into contact with a label and while in this position, the air is exhausted from the tubes 39 to cause the margin of the label to adhere to the suction plates. The tubes 39 are then rocked in the opposite direction to move said margin into the path of the nippers on the label applying drums. The means for thus rocking the suction tubes is fully described in the application already referred to. The upper ends of the suction tubes 39 are connected with the pump cylinder 20 by means of flexible tubes 42 which are in turn connected with nipples 44 that project from opposite sides of the pump cylinder and afford ('Oll'lll'llllllCzltlOIl with the interior thereof. Sutlicient slackness is provided in the tubes #12 to insure that the rocking of the cylinder 20 will not interfere with the. connections between the-cylinder and the suction tubes.

In order to render the suction plates 8 operative at the proper time, the cylinder 20 is constructed so that air will be exhausted from the interior of the suction tubes 39 during the movement of the piston 22 toward the right in Fig. 1. To this end a continuously open port 46 is provided at the rear extremity of the cylinder while at the forward end of the cylinder a passage 48 extends through the cylinder head 28 and is normally closed by a flapper valve 50. As shown, the passage +t8 terminates in a horizontal face 52 upon the upper side of the bearing 26 and the valve 50 is arranged to seat downwardly against said face. The valve 50 is carried by an arm 5s to which it is pivotally connected and which is, in turn, pivoted at 56 to the cylinder head 28. An extension 58 of the arm 5% enables the valve 50 to be conveniently opened at certain times as will be hereinafter explained.

As the piston 22 moves rearwardly and away from the piston head 28, air will exhaust freely through the port 46 without any tendency to be forced into the tubes 42. The tubes communicate with the interior of the pump cylinder at points so located with respect to the cylinder head that a predetermined degree of vacuum will be built up in the cylinder before any suction is applied to the suction plates 8. When the piston has travelled far enough upon its rearward or suction stroke to establish communication between the tubes 42 and the low pressure chamber at the left of the piston, the suction tubes will suddenly be connected with said low pressure chamber and apartial vacuum suddenly established in the suction tubes will enable the suction plates 8 to function to draw outwardly the adjacent edges of the foremost labels in the magazine 6 so that the labels may be seized by the nippers on the label applying drums 4 in the manner already described. This construction is considered an important feature of the present invention inasmuch as itenablesthe suction plates to function much more efi'ectively than if the suction plates were in communication with the low pressure chamber of the pump at the start of the suction stroke of the pump piston. Upon the return or forward movement of the piston 22, after normal pressure conditions have been reestablished in front of the piston, the valve 50 will open to permit free exhaust from forward end of the cylinder.

For the purpose of controlling the degree of suction developed by means of the described pump aud for permitting the same to be regulated at will, a valve (50 is providcd for permitting the entrance of air into the cylinder 20 at the left of the piston 22 when pressure in the cylinder has fallen to a predetermined amount. The valve 60 comprises a hollow cylindrical casing 62 one end of which is reduced in diameter, as indicated at 64, and is threaded into an aperture in the uppermost portion of the side wall of the pump cylinder. the valve casing (32 is internally screw threaded to receive the externally threaded reduced extension 66 of a cap 68. A vertical passage 70 extends upwardly from the lower extremity of the extension 66 of the cap and leading from opposite sides of said passage are two branch passages 72the passages 70 and 72 affording a means of communication between the interior and the exterior of the valve casing. At the lower extremity of the vertical passage 70 is a valve seat against which is normally seated a ball valve 74, the latter being held to its seat by a coiled spring 76. The upper end of the spring 76 engages the ball valve 7 4.- while the lowerportion of the spring fits within a bore in the reduced valve casing extension 64 and rests upon an internal annular shoulder formed at the lower extremity of said here. The interior of the valve casing 60 comn'iunicates with the interior of the pump cylinder through the bore 78 and through a port 80 at the lower extremity of the extension 64.

lVhen the pump piston 22, moving toard the right in Fig. 1, has passed beyond the port 80, communication becomes established between the interior of the valve casing 60 and the low pressure chamber at the left of the pump piston. When the pressure in the cylinder 20, at the left of the piston 22, has fallen to a predetermined point, due to the continued travel of said piston toward the right, atmospheric pressure, acting upon the top of the ball valve 74 will overbalance the force of the spring 7 6 so that the ball valve will be forced from its seat and air will enter the cylinder 20 throu h the port 80, relieving the suction cause b the partial vacuum within the pump ey inder.

To permit the action of the spring 7 6 upon the ball valve 74 to be adjusted so that the degree of suction developed by the pump may be regulated at will, a second spring 82 is confined within the passage 70 with its lower end bearin against the u per side of the ball valve and its upper end on- The upper portion of gaged by an adjusting screw 84 that is diminished to vary its action upon the ball valve and this to vary the degree of force necessary to over-balance the upward force of the spring 76. Thus the valve 60 may be adjusted at will so that it will operate to relieve the low pressure in the cylinder 20 when a predetermined amount of suction has been developed therein.

In the use of the wrapping and labelling machine to which the illustrated embodiment of the present invention is applied, it is sometimes desirable to wrap articles without applying labels thereto, and consequently it is desirable that the label applying mechanism shall be capable of running idly at such times. In accordance with the present invention the flapper valve 50 may be opened so that no suction Wlll be developed in the pump cylinder. Thus no labels will be acted upon by the suction plates 8 and as a result none will be transferred to the articles and applied thereto by the drums 4. The valve 50 may be conveniently raised by rocking backwardly the extension 58 of the arm 54- and said extension is so constructed anl arranged that when moved into engagement with the side wall of the pump cylinder, the valve 50 will have been elevated to such a position above the pivot pin 56 that it Will remain open until manually closed. When closed it will be held to its seat by gravity.

The aboved described air exhausting mechanism is of simple and practical construction and is particularly adapted for application to certain types, of machines such as that in connection with which it has been illustrated in the accompanying drawings. The construction of the present suction pump is such that it may be actuated in the required time relation to the machine to which it is applied by connecting its reciprocating piston directly to a reciprocating or oscillating member of said machine, such as the described oscillating arm 12. By constructing an air exhausting mechanism in such a manner that it may be actuated by an, oscillating or reciprocating member the device embodying the present invention is capable of being mounted at the top of the wrapping machine, as shown, where it is readily accessible for adjustment of its regulating valve 60 or to permit the opening of the valve 50 so that it may be rendered inoperative at will. The effectiveness of the operation of the suction plates is greatly increased by theconstruction and arrangement of the pump which enables a predetermined amount of vacuum to be built upinthe pump before the-suc-' tion plates are connected therewith so the latter will be able to exert a sufliciently strong pull upon the labels to insure that it will effectively erform its function.

The invention as been illustrated in an embodiment at present preferred but it is to be understood that the scope of the invention is defined by the appended claims rather than by the foregoing description.

What I claim is:

1. In a wrapping and labelling machine, the combination with an oscillatory member of the wrapping mechanism and a suct1on plate for periodically operating upon the labels in a supply magazine, of an air exhausting mechanism compr1s1ng a suction pump of the reciprocatory piston type connected with said suction plate and adapted and arranged to be actuated by direct connection of its piston with said oscillatory member so that said piston is moved in a suction stroke as the said plate operates upon a label.

2. In a label applying machine, the combination with a supply magazine for holdbuild up a predetermined amount of vacuum before permitting said vacuum to act upon thesuction plate.

3. In a wrapping machine provided with wrapper folding and label applying mechanism and havingan oscillatory feed member located above the wrapper folding mechanism, the combination with a supply magazine for holding a stack of labels and a,

suction plate periodically operative to move a portion of the foremost label of the stack into position to be seized by the label applying mechanism, of an air exhausting device for creating suction in the suction plate comprising a pump cylinder, a piston reciprocable in said cylinder located above the label applying mechanism, a piston rod connecting the piston directly with said oscillatory member, a tube connecting the interior of the pump cylinder with the suction plate, and means for mounting the pump cylinder to enable the piston rod to partake of the oscillatory movement of said member.

4. In a wrapping machine provided'with label applying mechanism and having an oscillatory feed member associated therewith, the combination with a supply magagine for holding a stack of labels and a;

for creating suction in the suction "plate inder, a

comprising i a pump cylinder pivotally mounted for rocking movement in the plane of oscillation of said member, a piston reciprocable in said cylinder, a piston rod rigidly connected at one end with saidp ston and pivotally connected at its opposite end with said oscillatory member, and a tube connecting the interior of the pump cylinder with the suction plate. I v

5. In a wrapping machine provided with label applying mechanism and havin an oscillatory feed member associated tierewith, the combination with a supply mag' azinc for holding a stack of labels and a suction plate periodically operative to move a portion of the foremost label ofthe stack into position to be seized by the label a plying mechanism, of an air exhausting evlce for creating suction in the suction plate comprising .a pump cylinderclosed at one end and open at the other and pivotally mounted for rocking movement in plane of oscillation of said member, a piston reciprocable in said cylinder, a piston rod slidable through the closed end of the cylinder and connecting the piston directly with said oscillatory member and a flexible tube connectin the interior of thepump cylinder with the suction plate.

6. In a'wrapping machine provided with labled applying mechanism and having an oscillatory feed member associated therewith, the combination with a supply magazine for holding a stack of labels and a suction plate periodically operative -to move a portion of the foremost label of the stack into position to be seized by the label applying mechanism, of an air exhausting device for creating suction in the suction plate comprising a ump cylinder continuously open at one en and having a cylinder head provided with an outlet passage at its opposite end, a piston reciprocable in said cyliston rod slidable through said cylinder head and connecting the piston with said oscillatory member, a conduit connecting the interior of said cylinder with said suction plate, a valve for closing the passage in the cylinder head during. the suction stroke of the piston and adapted to open upon the return stroke of the latter, and means for enabling said valve to be manually opened and maintained in open position to render the action of the iston inefi'ective to lower the pressure within the pump cylinder.

7. In a wrapping machine provided with label applying mechanism and havin an oscillatory feed member associated therewith, the combination with a supply magazie for holding a stack of labels and a suction plate periodically operative to move a portion of the foremost label of the stack into position to be seized by the label applying mechanism, of an air exhausting device for creating suction in the suction plate comprising a ump cylinder continuously open at one on and having a cylinder head provided with an outlet passage at its opposite end, a piston reciprocable in said cylinder, a piston rod slidable through said cylinder head and connecting the piston with said oscillatory member, a conduit connecting the interior of said cylinder with said suction plate, a flapper valve on the exterior of the pump cylinder adapted to be positioned by gravity to close the passage in' the cylinder head, during the suction stroke of the piston and to open upon the return stroke of said piston, an arm pivoted upon the pump cylinder-and having said valve pivotally mounted thereon, and an extension of said arm adapted to be manually engaged to facilitate the opening of the valve and by engagement with the cylinder to arrest said opening movement of the valve when the latter is so positioned relatively to the pivot of said arm that 'it will be maintained open until manually closed.

8. In a wrapping machine provided with label applying mechanism, the combination with a suction picker device for periodically moving a portion of the foremost label in a supply stack into the path of movement of the label applying mechanism, of a suction pump for exhausting air from said picker device and means on said pump for enablin the latter to operate idly when desired, sai means comprising a passage in the cylinder head adapted to admit air to breakthesuction during the suction stroke of the piston, a flapper valve movable by gravity into position to close said passage, an arm pivoted onthe exterior of the cylinder and carrying said valve, and an extension of said arm, constructed and arranged to serve as a handle to facilitatethe manual opening of said valve and to cooperate with the wall of thecylinder to maintain the valve in open position.

9. In a wrapping machine provided with label applying mechanism and having an oscillatoryfeed member associated therewith, the combination with a supply magazine for holding a stack of labels and a suction plate'pleriodically operative to move a portion of t e foremost label of the stack into position to be seized by the label applymg mechanism, of an air exhausting device for creating suction in the suction plate cylinder continuously comprising a um open at one en an having a cylinder head provided with an outlet assage at its opposite end, a piston reciprocable in said cylinder, a piston rod slidable through said cylinder head and connecting the piston with said oscillatory member, a conduit connect-- ing the interior of said cylinder with said suction plate, a valve for closing the outlet passage in the cylinder head during the suction stroke of the piston and for opening said passage upon the return stroke of said piston, and means for controlling the degree of vacuum within said cylinder comprising a valve casing in communication with the interior of said cylinder and having a passage connecting the interior of the valve casing with the atmosphere, a valve for closing said passage, a spring exerting a force against the valve in one direction to hold it closed, means for exciting a force against the valve in the opposite direction and tending to counter-balance the force of said spring, and means for adjusting said means to var y its counter-balancing effect.

10. In a wrapping machine provided with label applying. mechanism and having an oscillatory feed member associated therewith, the combination with a supply magazine for holding a stack of labels and a suction plate periodically operative to move a portion of the foremost label of the stack into position to be seized by the label apply ing mechanism, of an air exhausting device for creating suction in the suction plate comprising a pump cylinder continuously open at one end and having a cylinder head provided with an outlet passage at its opposite end, a piston reciprocable in said cylinder, a. piston rod slidable through said ylinder head and connecting the piston with said oscillatory member, a conduit connecting the interior of said cylinder with said suction plate, a valve for closing the outlet passage in the cylinder head during the suction stroke of the piston and for opening said passage upon the return stroke of said piston, and means for controlling the degree of vacuum within said cylinder comprising a valve casing in communication with the interior of the pump cylinder and having a passage connecting the interior of the valve casing with the atmosphere, a ball valve adapted to seat at the inne end of said passage to close the valve, a spring for holding said valve to its seat adapted to permit the valve to open only when the pressure in the pump cylinder has been re duced to a predetermined degree, and means operating upon said valve and capable of adjustment for rendering the same more or less quickly responsive to changes of pres sure in the pump cylinder.

11. In a wrapping machine provided with label applying mechanism and having an oscillatory feed member associated therewith, the combination with a supply magazine for holding a stack of labels and a suction plate periodically operative to move a portion of the foremost label of the stack into position to be seized by the label ap- 'ilying mechanism, of an air exhausting device for creating suction in the suction plate comprising a pump cylinder continuously open at one end and having a cylinder head inder, a piston rod slidable through said cylinder head and connecting the piston with said oscillatory member, a conduit connecting the interior of said cylinder-with said suction plate, a valve for closing the outlet passage in the cylinder head during the suction stroke of the piston and for opening said passage upon the return stroke of said piston, and means for controlling the degree of vacuum within said cylinder comprising a valve casing mounted upon the exterior of the pump cylinder, said valve casing being in communication with the interior of said cylinder and having a pas sage connecting the interior of the valve casing with the atmosphere, a ball valve adapted to seat at the inner end of said passage, a spring acting in one direction upon said valve to hold it to its seat, a second spring confined in said passage and acting in the opposite direction, upon said valve, and'means for varying the compression of the second spring toimpose a greater or less load upon the first spring and thereby to render the valve more or less quickly responsive to the reduction of pressure in the pump cylinder.

12. In a wrapping machine provided with label applying mechanism and having an oscillatory feed member associated therewith, the combination with a supply magazine for holding a stack of labels and a suction plate periodically operative to move a portion of the foremost label of tlie stack into position to be seized by the label applying mechanism, of an air exhausting device for creating suction in the suction plate comprising a pump cylinder continuously open atone end and having a cylinder head provided with an outlet passage at its opposite end, a piston reciprocable in said cylinder, a piston rod slidable through said cylinder head and connecting the piston with said oscillatory member, a conduit connecting the interior of'said cylinder with said suction plate, a valve for closing the outlet passage in the cylinder head during the suction stroke of the piston and for opening said passage upon the return stroke of said piston, and means for controlling the degree of vacuum within said cylinder comprising a cylindrical valve casing mounted upon the exterior of the pump cylinder, an axial passage at the inner end of said casing connecting the interior of the within the first passage for holding the load upon the first spring and thereby to valve to its seat, It second spring eontined render the valve more or less quickly rexvithin the second passage and tending to sponsive to the reduction of pressure with- 10 unseat the valve, and an adjusting screw in the pump cylinder. threzided into the outer end of said second 1111 estimony whereof I have afiixecl my passage. for varying the compression of the g ur seconcl spring to impose-a greater or less ELMER LOVELL SM'ITH.. 

